Abstract

The U.S. NRC is developing an advanced thermal hydraulic code named TRACE for safety analyses of nuclear power plants (NPPs). According to TRACE user’s manual, NRC has ensured that TRACE will be the main code used in thermal hydraulic safety analysis in the future, without further development of other thermal hydraulic codes such as RELAP5 and TRAC. SNAP is a program with graphic user interface, which processes the input and output of TRACE. As TRACE user’s manual describes, TRACE has a greater simulation capability than the other old codes, especially for events like loss-of-coolant accident (LOCA).

The Maanshan NPP operated by Taiwan Power Company is the only Westinghouse-PWR in Taiwan. The rated core thermal power is 2775 MWt. The reactor coolant system has three loops, each of which includes a reactor coolant pump and a steam generator. The pressurizer is connected to the hot-leg piping in loop 2. The Maanshan NPP TRACE model has been successfully established [1]-[3]. This study focuses on the establishment of the TRACE large break LOCA (LBLOCA) model for Maanshan NPP. Then, the TRACE LBLOCA analysis results compare with the FSAR data [4]. In this study, the LBLOCA is defined as a double-ended guillotine in cold-leg. The break is located in loop 1, which is one of the two loops that don’t have a pressurizer. For a LBLOCA analysis, the most important parameter is the peak cladding temperature (PCT). As defined by the 10 CFR 50.46 regulation [5], the PCT does not exceed 1477.6 K (2200℉). In this LBLOCA, the peak cladding temperature of TRACE calculated was 1358.8 K (1986℉).